Method of manufacturing solid-state electrolytic capacitor

ABSTRACT

A method of manufacturing solid electrolytic capacitors that can be directly connected to semiconductor components and have a faster response to a high frequency as well as a larger capacitance includes: a dielectric forming stage where a valve metal sheet ( 2 ) is made porous and a dielectric coating ( 7 ) is provided on the porous face ( 3 ); an element forming stage where a solid electrolytic layer ( 8 ) and a collector layer ( 10 ) are formed on the dielectric coating ( 7 ); and a terminal forming stage where a connecting terminal ( 16 ) for connecting to an external electrode is formed. The element forming stage includes the steps of forming the solid electrolytic layer ( 8 ); a forming through-hole electrode ( 9 ) in a through-hole ( 5 ) that is prepared on the valve metal sheet ( 2 ); and forming the collector ( 10 ) on the solid electrolytic layer ( 8 ).

TECHNICAL FIELD

The present invention relates to a method of manufacturing solidelectrolytic capacitors to be used in various electronic apparatuses.

BACKGROUND ART

A structure of a conventional solid electrolytic capacitor is describedhereinafter with reference to its manufacturing steps. (1) Form adielectric coating on a face of a porous section of a valve metal sheet,using one face in a thickness direction or a core of an intermediatesection of the porous valve metal sheet such as aluminum or tantalum asan electrode. (2) Form a collector layer on a surface of the dielectriccoating. (3) Form a capacitor element by providing an electrode layermade of metal on the collector layer. (4) Laminate the capacitorelements. (5) Gather together the electrode sections of respectivecapacitor elements laminated or electrode layers and couple them to anexternal terminal. (6) Finally, form an outer case such that theexternal terminal can be exposed.

The foregoing conventional solid electrolytic capacitor can increase itscapacitance and reduce its equivalent series resistance (hereinafterreferred to as ESR). In fact, this capacitor is mounted to a circuitboard via the external terminal similar to other ordinary solidelectrolytic capacitors.

The solid electrolytic capacitors, to be surface-mounted on circuitboards like semiconductor components, are obliged to have a slowresponse to a high frequency because the presence of terminal lengths orwire lengths increases ESR and equivalent series inductance (ESL) in anactual circuit.

In order to overcome the problem discussed above, both of an anode and acathode are placed on a surface of a solid electrolytic capacitor sothat semiconductor components can be directly mounted on the surface,and as a result, ESR and ESL can be lowered. Such a solid electrolyticcapacitor discussed above is proposed.

DISCLOSURE OF THE INVENTION

The present invention aims to provide a method of manufacturing thesolid electrolytic capacitors that can be directly connected tosemiconductor components and have a larger capacitance as well asfaster-response to a high frequency. The manufacturing method of thepresent invention comprises the following steps:

forming through-holes at given places after forming a resist film on aporous face of aluminum foil, one of both the foil faces having beenmade porous by etching; then

forming insulating films on the remaining face (non-porous face, andhereinafter referred to as a flat face) and on inner walls of thethrough-holes; then

forming a dielectric coating on the porous section after removing theresist film; and

forming a solid electrolytic layer on the dielectric coating; thenforming through-hole electrodes in the through-holes; and

forming a collector layer on the solid electrolytic layer; then formingopenings at given places of the insulating film on the flat face; and

forming connecting terminals on exposed faces of the openings and thethrough-hole electrodes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a solid electrolytic capacitor of thepresent invention.

FIG. 2 shows a sectional view of a solid electrolytic capacitor of thepresent invention.

FIG. 3 shows an enlarged sectional view of an essential part of a solidelectrolytic capacitor of the present invention.

FIG. 4 shows a sectional view illustrating a status where a resist filmis formed on a porous section of an aluminum foil of a solidelectrolytic capacitor of the present invention.

FIG. 5 shows a sectional view illustrating a status where through-holesare formed at given places on the aluminum foil of the solidelectrolytic capacitor of the present invention.

FIG. 6 shows a sectional view illustrating a status where insulatingfilms are formed on a flat face (non-porous face) of the aluminum foiland on inner walls of the through-holes of the solid electrolyticcapacitor of the present invention.

FIG. 7 shows a sectional view illustrating a status where a dielectriccoating is formed on the porous section of the aluminum foil of thesolid electrolytic capacitor of the present invention.

FIG. 8 shows a sectional view illustrating a status where a solidelectrolytic layer is formed on the dielectric coating on the aluminumfoil of the solid electrolytic capacitor of the present invention.

FIG. 9 shows a sectional view illustrating a status where through-holeelectrodes are formed in the through-holes of the solid electrolyticcapacitor of the present invention.

FIG. 10 is a sectional view illustrating a status where through-holeelectrodes are formed in the through-holes of the solid electrolyticcapacitor of the present invention.

FIG. 11 is a sectional view illustrating a status where openings areformed on the insulating film of the solid electrolytic capacitor of thepresent invention.

FIG. 12 is a sectional view illustrating a status where a connectingterminal is formed on the opening of the solid electrolytic capacitor ofthe present invention.

FIG. 13 is a sectional view illustrating a status where an outer case isprovided to a capacitor element of a solid electrolytic capacitor of thepresent invention.

FIG. 14 is a sectional view illustrating a status where externalterminals and connecting bumps are formed on the outer case of the solidelectrolytic capacitor of the present invention.

FIG. 15 is a sectional view illustrating a status where a resist film isformed on an insulating film of another solid electrolytic capacitor ofthe present invention.

FIG. 16 is a sectional view illustrating a status where a pattern isprovided to the resist film of the solid electrolytic capacitor shown inFIG. 15.

FIG. 17 is a sectional view illustrating a status where through-holeelectrodes are formed in through-holes of still another solidelectrolytic capacitor of the present invention.

FIG. 18 is a sectional view illustrating a status where a solidelectrolytic layer is formed on a dielectric coating on an aluminum foilof the still another solid electrolytic capacitor of the presentinvention.

FIG. 19 is a sectional view illustrating a status where an insulatingfilm is formed on a flat face of an aluminum foil and in through-holesof yet another solid electrolytic capacitor of the present invention.

FIG. 20 is a sectional view illustrating a status where a dielectriccoating is formed on a porous section of an aluminum foil of the solidelectrolytic capacitor shown in FIG. 19.

FIG. 21 is a sectional view illustrating a status where a solidelectrolytic layer is formed on the dielectric coating on the aluminumfoil of the solid electrolytic capacitor shown in FIG. 20.

FIG. 22 is a sectional view illustrating a status where secondthrough-holes are formed in the insulating film of the solidelectrolytic capacitor shown in FIG. 21.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The manufacturing method of the present invention comprises thefollowing steps:

forming a resist film on a porous section of aluminum foil, then formingthrough-holes at given places; and

forming insulating films on the remaining face (non-porous face, andhereinafter referred to as a flat face) and inner walls of thethrough-holes; then

removing the resist film; and then

forming a dielectric coating on the porous section.

A set of steps hitherto discussed is referred to as a stage of forming adielectric, and this stage is followed by the steps below:

forming a solid electrolytic layer on the dielectric coating; then

forming a through-hole electrode in the through-holes; and

forming a collector layer on the solid electrolytic layer.

A set of steps hitherto discussed is referred to as a stage of formingelements, and this stage is followed by the steps below:

forming openings at given places of the insulating film on the flat faceof the aluminum foil; and

forming connecting terminals at the openings and on the through-holeelectrodes.

A set of steps hitherto discussed is referred to as a stage of formingterminals.

The present invention allows the solid electrolytic capacitors to bedirectly coupled to semiconductor components, and provides amanufacturing method that can manufacture with ease the solidelectrolytic capacitors excellent in high frequency characteristics. Avariety of combinations of steps in a middle stream of themanufacturing-flow will produce various advantages. Some of thoseadvantages are listed below:

1. Solid electrolyte can be prevented from being formed on the flat faceof the aluminum foil, so that an anode and a cathode are positivelyseparated.

2. The through-hole electrode can be prevented from extending off theflat face of the aluminum foil, and also, the solid electrolyte can beprevented from being formed, so that the anode and the cathode arepositively separated.

3. A number of openings can be formed at a time.

4. Reliability of the insulation between the through-hole electrodes andthe aluminum foil can be strengthened.

A use of photosensitive resin or organic adhesive film allows formingholes at places agreeing with the through-holes by patterning, orpositively prevents the resist from entering the through-holes, so thata solid electrolytic layer is formed on the dielectric coating and inthe through-holes. A suitable method of forming resist film can beselected from immersion, spin-coating, screen-printing, or film-bonding,depending on the resist to be used, so that resist film can bepositively formed on the insulating layer.

Photoresist is applied to both the faces before patterning, and thethrough-holes are formed by wet-etching, so that a number ofthrough-holes can be formed at a time through a simple process. Asuitable method of forming through-holes can be selected from laser-beammachining, punching, drilling, or electrical discharge machining,depending on a diameter and the number of the through-holes, so that thethrough-holes can be formed at a lower cost.

Edges of the through-holes on the porous face of the aluminum foil canbe chamfered off, so that the number of occurrences of defectiveinsulation can be reduced.

A use of an electro-deposition method for forming an insulating filmallows the formation of a thin insulating film with a simple process.This electro-deposition method forms an insulating resin as the firstlayer, then forms the second layer made from insulating resin producedby mixing micro-gel, carbon fine particles and fine particles oftitanium oxide. In other words, the first layer is thin and has a highresistivity and the second layer can substantially cover edges, so thatthe film is formed with a uniform thickness. As a result, the insulatingfilm on the inner wall of the through-holes has a low defectiveinsulation rate. After conductive adhesive is filled in thethrough-holes for forming the through-hole electrodes, use of a curingmethod can produce capacitors with a simple process and highproductivity.

After a dielectric coating is formed, a resist film is formed on theentire face where an insulating film has been formed, then a solidelectrolytic layer is formed on the dielectric coating before the resistfilm is removed. This method prevents solid electrolyte from beingformed on the flat face of the aluminum foil, thereby positivelyseparating an anode and a cathode. There is another way to separate theanode from the cathode: After a dielectric coating is formed, a resistfilm is formed on the entire face where an insulating film has beenformed, then a through-hole electrode is formed in the through-holesbefore the resist film is removed. This method prevents the through-holeelectrode from extending off the flat face of the aluminum foil as wellas solid electrolyte from being formed on the flat face, so that theanode and the cathode are positively separated.

Use of laser-beam machining or grinding with the optimized output canform the openings with ease. Before an insulating film is formed, aresist section is formed on the flat face of the aluminum foil at agiven place, then a collector layer is formed before the resist film isremoved. This method can form a number of openings at a time with ease.

A use of conductive adhesive in forming a connecting terminal achievesexcellent productivity. Use of electro-plating or electroless-platingcan form a number of connecting terminals at a time.

Use of a composition formed of conductive polymers including aconjugated polymer containing a pi-electron as a material for the solidelectrolytic layer can form a solid electrolytic capacitor having alower ESR and being more thermostable. Use of chemical polymerization orelectrolytic polymerization realizes excellent productivity. Still othermethods are available as follows: Suspension of powder of a conductivepolymer is applied and dried, and then the conductive polymer is formedby electrolytic polymerization, so that stress applied to the dielectriccoating can be reduced. Manganese nitrate is pyrolized (heatdecomposition) to form manganese dioxide, so that solid electrolyticcapacitors can be manufactured positively by an established technique.Manganese nitrate is pyrolized (heat decomposition) to form manganesedioxide, and then the conductive polymer is formed by electrolyticpolymerization.

A collector is formed by use of a suspension of fine particles of carbonand by conductive adhesive, so that a solid electrolytic capacitorhaving a lower ESR than another solid electrolytic capacitor in whichconductive adhesive is directly applied to solid electrolyte.

The solid electrolytic capacitor of the present invention and a methodof manufacturing the same are demonstrated hereinafter with reference tothe accompanying drawings.

Exemplary Embodiment 1

The first exemplary embodiment is demonstrated with reference to FIG. 1through FIG. 14. FIG. 1 shows a perspective view of a solid electrolyticcapacitor in accordance with the first embodiment of the presentinvention. FIG. 2 shows a sectional view of the solid electrolyticcapacitor. FIG. 3 shows an enlarged sectional view of an essential partof the solid electrolytic capacitor.

First, a structure of sheet-like capacitor element 1 of the presentinvention is described following its manufacturing steps. Etch one ofthe faces of aluminum foil 2 to form a porous section (hereinafterreferred to as porous section 3), then form resist film 4 on the poroussection. Next, form through-holes 5 in aluminum foil 2 at given places,then form insulating films 6 on the non-porous face (flat face) and onthe inner walls of the through-holes. Remove resist film 4 and formdielectric coating 7 on porous section 3. Then form solid electrolyticlayer 8 on dielectric coating 7 before through-hole electrodes 9 areformed in through-holes 5. Next, collector layer 10 is formed on solidelectrolytic layer 8. Finally, form openings 11 on insulating film onthe flat face at given places, and form connecting terminals 12 atexposed faces of openings 11 and through-hole electrodes 9.

Provide outer case 13 on the lateral faces and collector layer 10, andform first external terminal 14 and second external terminal 15, whereterminal 14 is electrically coupled to aluminum foil 2 on outer case 13and terminal 15 is electrically coupled to collector layer 10. Then formconnecting bumps 16 both on through-hole electrodes 9 and connectingterminals 12, so that a solid electrolytic capacitor is built.

A manufacturing method of the solid electrolytic capacitor of thepresent invention is detailed hereinafter with reference to FIGS. 4-14.As shown in FIG. 4, one of the faces of the aluminum foil 2 is etchedand the one face becomes porous. Resist film 4 is formed on poroussection 3. A suitable method of forming the resist film can be selectedfrom immersion, spin-coating, and screen-printing. Photosensitive resinis applied to porous section 3 by one of the foregoing methods, and thenthe resin is dried, thereby obtaining resist film 4. Organic adhesivefilm can be used as resist film 4. In this case, resist film 4 is formedon porous section 3 by a film bonding method.

Next, as shown in FIG. 5, through-holes 5 are formed on aluminum foil 2at given places. A wet-etching method can form a number of through-holes5 at a time. Laser-beam machining, punching, drilling or electricdischarge machining is suitable to form through-holes 5 in any materialswith accuracy, and can form through-holes 5 as fine as not more than 100μm across.

In the case of using the wet-etching, first, form resist film havingopenings for through-holes on both the faces of aluminum foil 2, andthen form holes by the wet-etching before the resist film is removed,thereby forming through-holes 5. Further, chamfer the edges ofthrough-holes 5 on porous section 3 of aluminum foil 2 by thewet-etching, so that reliability of insulating film 6 later formed isincreased.

Next, as shown in FIG. 6, form an insulating coating by anelectro-deposition method, so that insulating film 6 can be formed onthe flat face of aluminum foil 2 as well as on the inner walls ofthrough-holes 5. The electro-deposition method can form a fine anduniform film, so that insulating film 6 does not fill up entire hole 5,but covers only the inner wall.

There is some possibility that insulating film 6 is thinly formed atedges of through-holes 5 on the face where dielectric coating 7 isformed, chamfering the edges is effective to solve this problem and alsoincreases insulation reliability. Further, insulating resin produced bymixing micro-gel, fine-particles of carbon and fine-particles oftitanium oxide, those materials being suitable for covering edges, iselectro-depositioned, thereby solving the problem more effectively.

The micro-gel discussed above is produced by adding polymeric particleshaving particle size of not more than 10 μm to a polymer, therebyincreasing a viscosity of the polymer. The micro-gel is hard to flow andsuitable for covering edges; however, in the case of providingelectro-deposition on the inner wall of through-hole 5 as fine as lessthan 100 μm across, more careful processing is required because themixed resin suitable for covering edges sometimes makes theelectro-deposition layer thick enough for through-hole 5 to be filled upwith the mixed resin. Thus the process of forming insulating film 6 byelectro-desposition is split into two steps. First, provide thin resinof high resistivity as a first layer, then provide insulating resinformed by mixing micro-gel, fine particles of carbon and fine particlesof titanium oxide, those materials suitable for covering edges, as asecond layer. As a result, insulating film 6 of fewer insulation defectsis formed on the inner wall of through-holes 5.

Next, as shown in FIG. 7, after resist film 4 is removed, anodizing inacidic solution allows forming dielectric coating 7 on porous section 3of aluminum foil 2. Then as shown in FIG. 8, solid electrolytic layer 8is formed on dielectric coating 7. This layer 8 is formed by forming apolymer layer using a conjugated polymer containing a pi-electron suchas polypyrrole or polythiophene, and/or a composition includingconductive polymers other than those discussed above through chemical orelectrolytic polymerization. Solid electrolytic layer 8 can be formed byelectrolytic polymerization or by only chemical polymerization after theconductive polymer is pre-coated by chemical polymerization. Theconductive polymer can be formed by electrolytic polymerization afterthe suspension of powder of the conductive polymer is applied and dried,or manganese nitrate is impregnated before thermal decomposition,thereby forming manganese dioxide, and then the conductive polymer canbe formed by electrolytic polymerization. There is another establishedtechnique to form solid electrolytic layer 8: Manganese nitrate isthermally decomposed to form manganese dioxide. This method can producea fine electrolytic layer, and adjust a thickness of the layerarbitrarily, so that the productivity and reliability can be improved.

As shown in FIG. 9, the step of forming through-hole electrode 9 inthrough-hole 5 is described. As a material of electrode 9, conductiveadhesive formed by mixing conductive particles such as Ag paste and Cupaste, is filled into through-hole 6, and then cured.

As shown in FIG. 10, collector layer 10 is formed on solid electrolyticlayer 8. Collector layer 10 is produced by laminating a carbon layer anda Ag-paste layer with conductive adhesive of which major components area suspension of carbon fine-particles and a Ag-paste. This structureallows drawing electric-charges more efficiently.

As shown in FIG. 11, openings 11 are formed at given places oninsulating film 6 prepared on the flat face of aluminum foil 2 with aYAG laser or a grinding method. Another method for forming openings 11is, to form a resist section at first on a given place on the flat faceof aluminum foil 2, then form collector layer 10 before the resistsection is removed, and finally remove the resist on the given place.

Next, as shown in FIG. 12, connecting terminal 12 is formed on theexposed face in opening 11 of insulating film 6 by using one of aconductive adhesive, electroplating or electroless-plating.

Then as shown in FIG. 13, outer case 13 made from epoxy resin, good forelectrical insulation and resistance to humidity, is formed aroundcapacitor element 1 for protecting element 1 from external stress,thereby increasing the reliability. Next, as shown in FIG. 14, firstexternal terminal 14 electrically coupled to aluminum foil 2, and secondexternal terminal 15 electrically coupled to collector layer 10 areformed on outer case 13, so that capacitor element 1 is completed.

It is desirable to form connecting bumps 16 on connecting terminals 12and through-hole electrodes 9 in order to increase the connectingreliability between the capacitor and semiconductor components orelectronic components.

The method discussed above can readily produce the solid electrolyticcapacitors that can be directly connected to semiconductor componentsand have a faster response to a high frequency.

Exemplary Embodiment 2

The second exemplary embodiment of the present invention is demonstratedhereinafter with reference to FIG. 15 and FIG. 16.

Etch one of the surfaces of aluminum foil 2 to form a porous section(hereinafter referred to as porous section 3), and then form resist film4 on the porous section. Next, form through-holes 5 in aluminum foil 2at given places, and then form insulating films 6 on the non-porous face(flat face) and on the inner walls of through-holes 5. Remove resistfilm 4 and form dielectric coating 7 on porous section 3. Those stepsare the same as those in the first embodiment.

Then solid electrolytic layer 8 is formed on dielectric coating 7. Atthis time, when the through-hole is not less than 80 μm across, solidelectrolytic layer 8 can be sometimes formed on insulating film 6prepared on the flat face of aluminum foil 2. This problem can beovercome by the following methods: First, as shown in FIG. 15,photosensitive resin is applied on insulating film 6 by one ofimmersion, spin-coating, or screen-printing, then the photosensitiveresin is cured for obtaining second resist film 17. Another way is this:adhesive organic film 6 can be used as second resist film 17. In thiscase, the organic film is formed on insulating film 6 by a film bondingmethod. Then as shown in FIG. 16, form holes on second resist film 17 ingiven dimensions at given places corresponding to through-holes 5 by aphoto-process or a machining method.

Next, form solid electrolytic layer 8 and through-hole electrode 9 bythe same methods as the first embodiment, and then remove second resistfilm 17, so that solid electrolytic layer 8 is not formed on the flatface of aluminum foil 2. As a result, an anode and a cathode can bepositively separated.

Then, prepare collector layer 10 on solid electrolytic layer 8 by thesame method as the first embodiment, and form openings 11 at givenplaces on insulating film 6 prepared on the flat face of aluminum foil2. Then form connecting terminals 12 on the exposed faces of opening 11and through-hole electrodes 9.

As discussed above, the second exemplary embodiment provides amanufacturing method of the solid electrolytic capacitors, and themethod can prevent solid electrolytic layer 8 from reaching to openings11 later formed, so that the anode and the cathode are positivelyseparated.

Exemplary Embodiment 3

The third exemplary embodiment of the present invention is demonstratedhereinafter with reference to FIG. 17 and FIG. 18, which illustratemajor steps of a method of manufacturing the solid electrolyticcapacitors in accordance with the third embodiment.

Etch one of the surfaces of aluminum foil 2 to form a porous section(hereinafter referred to as porous section 3), and then form resist film4 on the porous section. Next, form through-holes 5 in aluminum foil 2at given places, and then form insulating films 6 on the non-porous face(flat face) and on the inner walls of the through-holes. Remove resistfilm 4 and form dielectric coating 7 on porous section 3. Those stepsare the same as those in the first embodiment.

Then solid electrolytic layer 8 is formed on dielectric coating 7. Atthis time, when the through-hole is not less than 80 μm across, solidelectrolytic layer 8 can be sometimes formed on insulating film 6prepared on the flat face of aluminum foil 2. This problem can beovercome by the following methods: As shown in FIG. 17, through-holeelectrode 9 is formed in through-hole 5. As a material of electrode 9,conductive adhesive formed by mixing conductive particles such as Agpaste and Cu paste is filled into through-hole 5, and then cured. Thenas shown in FIG. 18, solid electrolytic layer 8 is formed on dielectriccoating 7, and collector layer 10 is formed on solid electrolytic layer8. This method prevents solid electrolytic layer 8 from being formed onthe flat face of aluminum foil 2.

Through-hole electrode 9 is prevented from extending off the flat faceof aluminum foil 2 by the following method: After dielectric coating 7is formed, second resist film 17 is formed on the entire face ofinsulating film 6. Next, through-hole electrode 9 is formed inthrough-hole 5, and solid electrolytic layer 8 is formed on dielectriccoating 7, then collector layer 10 is formed on top of that. Finally,second resist film 17 is removed. This method prevents the solidelectrolyte from being formed on the flat face of aluminum foil 2 aswell as through-hole electrode 9 from extending off the flat face.

Openings 11 are formed at given places on insulating film 6 prepared onaluminum foil 2 by YAG laser. This is the same process as the firstembodiment. Another method to form openings 11 is available: Beforeinsulating film 6 is prepared, a resist section is formed in advance ata given place on the flat face of aluminum foil 2 using photo-curableresin. The resist section is removed after the collector layer isformed. Connecting terminals 12 are formed on exposed faces of openings11 and through-hole electrodes 9.

As discussed above, the third exemplary embodiment provides amanufacturing method of the solid electrolytic capacitors, and themethod can prevents solid electrolyte from infiltrating into openings 11later formed, so that the anode and the cathode are positivelyseparated.

Exemplary Embodiment 4

The fourth exemplary embodiment of the present invention is demonstratedspecifically hereinafter with reference to FIG. 19 through FIG. 22,which illustrate major steps of a method of manufacturing the solidelectrolytic capacitors in accordance with the fourth embodiment.

Etch one of the surfaces of aluminum foil 2 to form a porous section(hereinafter referred to as porous section 3), and then form resist film4 on porous section 3. Next, form through-holes 5 in aluminum foil 2 atgiven places, and then form insulating films 6 on the non-porous face(flat face) and on the inner walls of the through-holes. Remove resistfilm 4 and form dielectric coating 7 on porous section 3. Those stepsare the same as those in the first embodiment.

Then solid electrolytic layer 8 is formed on dielectric coating 7. Atthis time, when the through-hole is not less than 80 μm across, solidelectrolytic layer 8 can be sometimes formed on insulating film 6prepared on the flat face of aluminum foil 2. This problem can beovercome by the following methods: As shown in FIG. 19, insulating film6 is formed such that the flat face of aluminum foil 2 is entirelycovered and first through-hole 5 is completely filled up with film 6. Inorder to fill up through-hole 5 completely, insulating film 6 can beformed by repeating electro-deposition of insulating resin severaltimes, or using screen printing or potting of the insulating resin.Next, as shown in FIG. 20, dielectric coating 7 is formed on poroussection 3, and then as shown in FIG. 22, second through-holes 18 areformed in insulating film 6. This structure prevents solid electrolyticlayer 8 from being formed on the flat face of aluminum foil 2.

Steps following the processes discussed above are the same as the firstembodiment. To be specific, after through-hole electrodes 9 are formedin second through-holes 18, collector layer 10 is prepared on solidelectrolytic layer 8, and openings 11 are formed at given places oninsulating film 6 prepared on aluminum foil 2. Then connecting terminals12 are formed on exposed faces of opening 11 and through-hole electrodes9.

As discussed above, the fourth exemplary embodiment provides amanufacturing method of the solid electrolytic capacitors. The methodcan increase insulation reliability between through-hole electrodes 9and aluminum foil 2, and prevent solid electrolyte from reaching toopenings 11 later formed, so that the anode and the cathode arepositively separated.

Industrial Applicability

The manufacturing method disclosed in the present invention can readilymanufacture the solid electrolytic capacitors that can be connecteddirectly to semiconductor components and have a faster response to ahigh frequency as well as a large capacitance.

What is claimed is:
 1. A method of manufacturing a solid electrolyticcapacitor, the method including: a dielectric forming stage where adielectric coating is formed on a porous surface of a valve metal sheet,an element forming stage where a solid electrolytic layer and acollector layer are formed on the dielectric coating, and a terminalforming stage where a connecting terminal to an external electrode isformed, wherein the dielectric forming stage comprises steps in theorder of: (A1) etching a first face of the valve metal sheet forproducing a porous section; (A2) forming a first resist film on thefirst face having the porous section; (A3) forming a through-hole on thefirst face at a given place; (A4) forming an insulating film on a secondface of the valve metal sheet and on inner wall of the through-hole; and(A5) forming a dielectric coating after the first resist film isremoved, wherein the element forming stage comprises the steps of: (B1)forming a solid electrolytic layer on the dielectric coating; (B2)forming a through-hole electrode in the through-hole; and (B3) forming acollector layer on the solid electrolytic layer; wherein the terminalforming stage comprises the steps of: (C1) forming an opening at a givenplace on the insulating film formed on the second face of the valvemetal sheet; and (C2) forming a connecting terminal on exposed faces ofthe opening and the through-hole electrode.
 2. The method ofmanufacturing the solid electrolytic capacitor of claim 1, wherein theelement forming stage comprises the steps in the order of (B1), (B2) and(B3).
 3. The method of manufacturing the solid electrolytic capacitor ofclaim 2, wherein the element forming stage further comprises the stepsof: forming a second resist film on the insulating film before step(B1); and removing the second resist film following step (B1).
 4. Themethod of manufacturing the solid electrolytic capacitor of claim 1,wherein the element forming stage comprises the steps in the order of(B2), (B1) and (B3).
 5. The method of manufacturing the solidelectrolytic capacitor of claim 1, wherein the element forming stagefurther comprises the steps of: (B4) forming a second resist film on theinsulating film before step (B2), and (B5) removing the second resistfilm, wherein the element forming stage comprises the steps in the orderof (B4), (B2), (B1), (B3) and (B5).
 6. The method of manufacturing thesolid electrolytic capacitor of claim 1, wherein the dielectric formingstage includes the step of forming a third resist film on the secondface simultaneously with step (A2), wherein the element forming stagecomprises the steps in the order of (B1), (B2) and (B3), and wherein theterminal forming stage includes the steps of: removing the third resistfilm; and forming an opening at a given place on the second face.
 7. Themethod of manufacturing the solid electrolytic capacitor of claim 1,wherein the dielectric forming stage includes the step of forming athird resist film on the second face simultaneously with step (A2),wherein the element forming stage comprises the steps in the order of(B2), (B1) and (B3), and wherein the terminal forming stage includes thesteps of: removing the third resist film; and forming an opening at agiven place on the second face.
 8. The method of manufacturing the solidelectrolytic capacitor of claim 1, wherein the dielectric forming stageincludes the step of forming the insulating film such that the secondface of the valve metal sheet is covered and the through-hole is filledup with the insulating film, wherein the element forming stage comprisesthe steps in the order of step (B1); the step of forming a secondthrough-hole in the through-hole filled up with the insulating film; thestep of forming the through-hole electrode in the second through-hole;and step (B3).
 9. The method of manufacturing the solid electrolyticcapacitor of claim 1, wherein one of photosensitive resin and adhesivephotosensitive film is used as the resist film.
 10. The method ofmanufacturing the solid electrolytic capacitor of claim 1, wherein theresist film is formed by a method selected from the group consisting ofimmersion, spin coating, screen printing, and film laminating.
 11. Themethod of manufacturing the solid electrolytic capacitor of claim 1,wherein step (A3) includes applying photoresist on both the faces of theporous valve metal sheet, and wet-etching a patterned opening.
 12. Themethod of manufacturing the solid electrolytic capacitor of claim 1,wherein step (A3) is carried out by a method selected from the groupconsisting of laser-beam machining, punching, drilling, andelectric-discharge machining.
 13. The method of manufacturing the solidelectrolytic capacitor of claim 1, wherein step (A3) further includeschamfering edges of the through-hole formed on the first face.
 14. Themethod of manufacturing the solid electrolytic capacitor of claim 1,wherein step (A4) uses an electro-deposition method to form theinsulating film.
 15. The method of manufacturing the solid electrolyticcapacitor of claim 14, wherein step (A4) includes forming insulatingresin as a first layer; and forming insulating resin as a second layerby mixing micro-gel, fine carbon particles and fine particles oftitanium oxide.
 16. The method of manufacturing the solid electrolyticcapacitor of claim 1, wherein step (B2) uses conductive adhesive to formthe electrode.
 17. The method of manufacturing the solid electrolyticcapacitor of claim 1, wherein step (C1) is carried out by one oflaser-beam machining and grinding.
 18. The method of manufacturing thesolid electrolytic capacitor of claim 1, wherein step (C2) usesconductive adhesive to form the terminal.
 19. The method ofmanufacturing the solid electrolytic capacitor of claim 1, wherein step(C2) is carried out by at least one of electro-plating and electrolessplating.
 20. The method of manufacturing the solid electrolyticcapacitor of claim 1, wherein step (B1) uses a composition including aconductive polymer to form the solid electrolytic layer.
 21. The methodof manufacturing the solid electrolytic capacitor of claim 20, whereinthe conductive polymer is a conjugated polymer containing a pi-electron.22. The method of manufacturing the solid electrolytic capacitor ofclaim 1, wherein step (B1) uses at least one of a chemicalpolymerization method and an electrolytic polymerization method.
 23. Themethod of manufacturing the solid electrolytic capacitor of claim 1,wherein step (B1) includes forming a polymer film using suspension ofpowder of the conductive polymer, and providing electrolyticpolymerization on the polymer film.
 24. The method of manufacturing thesolid electrolytic capacitor of claim 1, wherein step (B1) includesforming the solid electrolytic layer comprising manganese dioxide bythermally decomposing manganese nitrate.
 25. The method of manufacturingthe solid electrolytic capacitor of claim 24, wherein step (B1) includesforming conductive polymer by electrolytic polymerization following theprocess of forming the manganese dioxide.
 26. The method ofmanufacturing the solid electrolytic capacitor of claim 1, wherein step(B3) uses suspension of fine carbon particles, and conductive adhesiveto form the collector layer.